Here's the thing... NATO nor us is going to do anything more than lodge formal complaints if the Russians really are occupying the "rebel" areas of Ukraine. Why?
A. Putin knows we have a full potato as President and won't do anything other than complain (he knew this from 2009-2017 as well)
B. Putin knows good and well West Europe depends on the gas flow to survive the winter and our chief full potato's environmental stance won't allow additional drilling or exploitation of the resources we could have to help with that.
C. NATO is in no position to actually project force in Ukraine since our full potato in chief has our military in a scramble over being diversified and is rooting out "possible domestic terrorists."
D. Putin knows sanctions won't do a damn bit of good against Russia since they've already been under sanctions before and many, if not most other nations could care less about the Donbass or any other area of Ukraine. (see Iran)
E. China is remaining neutral at best and, at worst, tacitly supporting it which gives the UN Security Council zero legs
F. Putin is probably one of the craftiest world politicians and master geopolitical chess player (whether you like him or not, one can admit that) and he will not do something without knowing what he's getting into. Hence, if he thinks he can invade Ukraine... or occupy certain areas and get away with it, he will. That die was cast a long time ago.
G. The majority of our own country could give a hootie damn about Ukraine (no offense to any Ukrainians reading this) because they have lost faith in our military and the political powers that be to actually fight and win in a conflict. (see Afghanistan)
H. Putin knows our own political landscape is so fractured we couldn't agree on a response to the threat, hence, he had free reign to do what he wants.
And there you have it.